TY - JOUR
T1 - Quantum resolved studies of electron-stimulated reactions on adsorbate covered Pt(111) surfaces
AU - Orlando, T. M.
AU - Burns, A. R.
AU - Stechel, E. B.
AU - Jennison, D. R.
N1 - Funding Information:
The authors are indebted to M.E. Bartram for allowing us to study his UPS experimental data prior to publication. We also thank W. Ho, W. Mieher, T. D. Raymond and A. Smith for helpful discussions. This work was supported by the U.S. Department of Energy under Contract DE-AC04-76DP00789.
PY - 1991/6/2
Y1 - 1991/6/2
N2 - Using laser resonance-enhanced ionisation spectroscopy, we have studied electron (6-350 eV) stimulated dissociation of NO2 coadsorbed with up to 0.75 monolayer of atomic O on Pt(111). Several dramatic effects on NO2 dissociation occur due to the presence of O. There is a large ( × 26) enhancement in the specific dissociation yield, a narrowing of the NO translational energy distributions, and a distinct propensity ( > 4:1 at low J) for populating the upper Ω = 3 2 NO spin-orbit level over the Ω = 1 2 level. The spin-orbit state distribution of the O(3PJ) dissociation fragment is (5.0): (2.5): (1.0) for J = 2, 1 and 0, which is within experimental error of the statistical (T → ∞) 2J + 1 limit. The enhanced yield probably results from an increased excited state lifetime due to a reduction in substrate charge-transfer screening. We have also detected O(3PJ = 2,1,0) and NO X2 Π 3 2, 1 2(v = 5) above an electron (6-350 eV) beam irradiated Pt(111) surface containing coadsorbed O2 and NO at 90 K. We conclude that both O(3PJ) and NO(v = 5) are laser-induced photodissociation fragments of NO2 desorbates. The NO2 is probably the reaction product of a collision between an O atom (created by electron-stimulated dissociation of adsorbed O2) and an NO(a). We correlate the 10 eV NO2 production threshold with the dissociative ionization of the 3σg molecular bonding orbital of O2(a).
AB - Using laser resonance-enhanced ionisation spectroscopy, we have studied electron (6-350 eV) stimulated dissociation of NO2 coadsorbed with up to 0.75 monolayer of atomic O on Pt(111). Several dramatic effects on NO2 dissociation occur due to the presence of O. There is a large ( × 26) enhancement in the specific dissociation yield, a narrowing of the NO translational energy distributions, and a distinct propensity ( > 4:1 at low J) for populating the upper Ω = 3 2 NO spin-orbit level over the Ω = 1 2 level. The spin-orbit state distribution of the O(3PJ) dissociation fragment is (5.0): (2.5): (1.0) for J = 2, 1 and 0, which is within experimental error of the statistical (T → ∞) 2J + 1 limit. The enhanced yield probably results from an increased excited state lifetime due to a reduction in substrate charge-transfer screening. We have also detected O(3PJ = 2,1,0) and NO X2 Π 3 2, 1 2(v = 5) above an electron (6-350 eV) beam irradiated Pt(111) surface containing coadsorbed O2 and NO at 90 K. We conclude that both O(3PJ) and NO(v = 5) are laser-induced photodissociation fragments of NO2 desorbates. The NO2 is probably the reaction product of a collision between an O atom (created by electron-stimulated dissociation of adsorbed O2) and an NO(a). We correlate the 10 eV NO2 production threshold with the dissociative ionization of the 3σg molecular bonding orbital of O2(a).
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U2 - 10.1016/0168-583X(91)95888-K
DO - 10.1016/0168-583X(91)95888-K
M3 - Article
AN - SCOPUS:25544434463
SN - 0168-583X
VL - 58
SP - 477
EP - 484
JO - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
JF - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
IS - 3-4
ER -